Service stations in ink-jet printers are intended to maintain a thermal ink-jet printhead in good working order for the service life of the printhead. As is well-known to those skilled in this art, the printhead is formed as part of a printing cartridge. The cartridge contains a reservoir of ink, and the printhead contains an assembly of passageways, firing elements (resistors) and nozzles for firing droplets of ink toward a printing medium, such as paper.
During the course of operation, it is possible for nozzles to become clogged with ink and for bubbles of air to be trapped in such a manner as to interfere with the proper operation of the printhead. Also, it is desirable to prevent contaminants, such as paper dust, from affecting the operation of the nozzles and to prevent ink from drying in the nozzles when the printhead is at rest. Finally, it is desirable to clear out soft viscous plugs of ink, which may form while the printhead is at rest. This should be done prior to initiation of printing, to ensure that all nozzles in the orifice plate of the printhead are firing properly.
A service station can address the afore-mentioned problems and requirements. While service stations are not per se novel in thermal ink-jet printing, it is a goal to provide a service station with easy operation which maximizes a number of functions in a minimum of space. The preferred service station has a number of functions, including:
1. clear clogged nozzles and remove bubbles; PA1 2. cover nozzles when the printhead is not in use to prevent contamination thereof; PA1 3. prevent ink from drying out in the nozzles when the printhead is not in use; PA1 4. wipe contaminants picked up during printing off of nozzles; and PA1 5. provide a location to fire nozzles into for clearing out the soft viscous plugs of ink. PA1 (a) pump means for priming the printhead, PA1 (b) a sled to actuate the service station and including means to seal the printhead, and PA1 (c) wiping means for cleaning the printhead.